Design Of Control Module For Density Logging While Drilling Tool

Density-logging tool measures the desity of stratum by utilizing Compton Effect produced by gamma-ray interaction with the formation.Radioactive source is typically a Cs137 source,which emits gamma rays with energy of 0.66 MeV.When gamma rays interact with electrons in the stratum,Compton Scattering dominates over all other effects.The count rates that detecters can record depends on the average electron density in the volume of formation.As the density-logging tool is part of drill string and real-time mesurement result can't be completely uploaded simultaneously,the data should be stored in storage module.This thesis is based on the theory of density logging while drilling and took an eye on the detail design of the control module of density logging while drilling tool,including circuit design,coding and analysis of logging result.The overall task for the module can be divided into two groups.One group of tasks should be done when not drilling.Another group of tasks should be done while drilling.The first group of tasks include: control for storage module which contains memory checking,erasing,reading and programming;help to control cliper circuit which contains erasing and parameter setting commands;receive different kinds of parameters for agorithm,sector numbers and synchcronize time.Another group of tasks include: receive,process and store measurement data captured by analog circuit;respond to command sent by main controller including real-time result uploading.By sorting the tasks that should achieved by this module,the way to design circuit is specified and coding is simplified.Lastly,all the functionalities are verified and all the requirements are met.